This invention relates to a polished rod protector and receiver and, more particularly, to an improved reinforced extensible and collapsible shroud for a polished rod and an improved liquid receiving container used in conjunction with the polished rod. While not limited thereto, the protector of this invention is particularly useful with polished rods having a high extension factor, as in oil wells for example.
In the oil well pumping art, polished rods are used to connect a string of sucker rods which actuate a pump at the bottom of the well to the external means of reciprocation. The polished rod extends through a stuffing box which includes packing for closely engaging the reciprocating polished rod to prevent the fluid product of the well from escaping. In its extended position a considerable portion of the polished rod projects above the stuffing box, and unless protected, is exposed to atmospheric dust and other foreign abrasive particles which tend to accumulate on the reciprocating rod and be carried therewith to the packing within the stuffing box. Such accumulations are abrasive, and cause the polished rod and the packing to wear excessively, resulting in leakage therebetween and requiring frequent replacement thereof. The frequency of replacement has a direct relation to economy of operation, and leakage of the fluid product poses an environmental pollution problem of increasing concern.
It has been proposed to protect polished rods by enclosing the projecting portion thereof in an elongated, extensible bellows having a plurality of convolutions intended to permit contraction and extension thereof in a mannner accommodating retraction and extension of the reciprocating rod. See, for example, U.S. Pat. Nos. 3,186,722 and 3,270,810.
While this proposal has merit, it has not heretofore been adopted because the bellows must be capable of repeated extension to a length several times its retracted length, and a typical bellows is neither intended for nor capable of operation over such a range. The problem arises because a typical oil well polished rod will project only a few inches from the stuffing box when retracted, and as much as nine feet or more when extended. If a typical bellows capable of being collapsed to a length of a few inches is extended several feet it is stretched beyond its capabilities. The bellows material does not stretch uniformly but puckers, creating zones of weakness and resulting in rapid failure of the bellows.
The polished rod protector disclosed in application Ser. No. 249,261 overcomes these problems and provides a convoluted protector shroud capable of such extension and in which the outer diameter portions are reinforced against radial collapse. However, the shroud is capable of lateral movement which could result in wear-producing contact between the polished rod and the inner diameter portions of the shroud and it is desirable to prevent this.
In addition, it is desirable to provide a receiver for liquids and gases which may leak past the stuffing box, thereby to control the disposal thereof. Such liquids include oil and salt water, and it is known to accumulate them in a receiver having an overflow discharge. However, because oil floats on water the oil component normally will discharge first with the result that its benefits as a lubricant are lost to the reciprocating rod which is instead exposed to the corrosive effect of the retained salt water which may also contain various deleterious contaminants.
In the absence of such lubrication, the rod can heat up, for example when pumping dry at the start of a cycle, which can be destructive of the packing particularly when the latter has been tightened against the rod in an effort to compensate for wear.
Also, oil well polished rods are very apt to shift position as they reciprocate and move into and out of alignment. This poses a problem with conventional rod wiper elements, which generally are fixedly mounted and do not readily accommodate such lateral positional shifting and/or wobbling of the rod during reciprocation thereof.
In addition, it is customary to intermittently partially rotate polished rods, both to prevent uneven wear of the rod as it reciprocates in the stuffing box, and to actuate paraffin scrapers in the well casing.